Spectrophotometric-type instruments are known and used in a variety of applications. An instrument of this type and an associated patient interface optical probe are, for example, disclosed in the Anderson et al. U.S. Pat. No. 5,879,294. The probe includes a housing and a number of optical fibers. The optical fibers terminate at a tissue-facing surface of the probe and are coupled between the probe and instrument within a cable housing. The embodiment of the probe shown in the Anderson et al. Patent has several send fibers through which light of different wavelengths is transmitted from the instrument to the probe. The tissue-facing surface of the probe is positioned in contact with the tissue being analyzed to transmit the light from the send fibers into the tissue. The receive fiber collects light that has traveled through the tissue being analyzed and transmits the collected light back to the instrument for processing.
There remains a continuing need for improved optical probes for use with spectrophotometric instruments. To provide accurate measurements it is important for the probe to maximize the coupling of the measurement light between the optical fibers and the tissue. In particular, it is important to maximize the coupling of the light emitted from the ends of the send fibers into the tissue, and to maximize the coupling of the collected light back to the receive fibers. Measurement accuracy can also be enhanced by minimizing the amount of ambient light that enters the receive fibers. The probe should be capable of providing a high degree of hygiene. A probe which provides these features and which is efficient to manufacture and convenient to use would be especially desirable.